DIY PCB TUTORIAL
DISCLAIMER: MAKING PRINTED CIRCUIT BOARDS AT HOME INVOLVES THE USE OF DANGEROUS CHEMICALS AND POWER TOOLS. THIS TUTORIAL IS INTENDED FOR PEOPLE WHO ALREADY HAVE EXPERIENCE MAKING PRINTED CIRCUIT BOARDS, BUT WOULD LIKE TO TRY A DIFFERENT METHOD. IF YOU ARE A BEGINNER PLEASE SEARCH THE INTERNET FOR OTHER SOURCES ON BUILDING PRINTED CIRCUIT BOARDS BEFORE ATTEMPTING THIS METHOD. ALTHOUGH I FIND THIS METHOD TO BE FOOL PROOF YOU MAY GET VARIED RESULTS WHICH WILL REQUIRE EXPIRIMENTATION TO OBTAIN 100% REPEATABILITY. When I first started toying with circuits the idea of making my own printed circuit boards without too much money invested seemed impossible. Like many electronics hobbyists I started by using the “photo method” and purchased UV lights, developing chemicals, laser transparencies, pre-sensitized boards, glass, etc. Although it was pretty costly, I was able to get good results after a few botched attempts. The problem with this method is that not only was there extra money involved, but the set up was too elaborate for my bathroom “laboratory” in my one bedroom apartment. I had begun looking into different products that use the toner transfer method. The toner transfer method involves using a laser printer to print your circuit layout onto a special piece of paper and then using heat to adhere the printout onto a copper clad board. This special paper has an emulsion that allows the toner to release from the paper after the heat is applied leaving the toner on the PCB. Although not as costly as using the photo method, the special paper sold for this purpose can really start to add up in cost if you make a mistake during transfer or if the printer doesn’t print the image properly. Not only that, but I’ve only been able to find online stores that carry it so it isn’t readily available if you run out. After lots of frustration and hundreds of dollars spent I decided to try to find a paper that had similar qualities to the special toner transfer paper, but was cheaper and easier to obtain. My answer came in the form of magazines. I started printing my images onto pages ripped from magazines, and I would run the copper clad and magazine page through a laminator to adhere the image to the copper clad. I’d then soak the copper clad in warm water for a few minutes which would release the paper from the copper clad, but leave behind the toner. I’d etch the boards in ferric chloride, and then drill them with my drill press. VOILA! I was successfully making printed circuit boards using paper I already had (magazines), my laser printer, a laminator, ferric chloride, copper clad board. Anyone with a local Radio Shack, office supply store, hardware store, and convenience store has immediate access to all of these items needed to make printed circuit boards. Before you start please realize that different magazine papers will provide varied results. A certain amount of experimentation is expected, but the upside is that you won’t be wasting money while working toward the best results. What you will need:
-Laser Printer -Copper clad board -Scotch pads, Brillo pads, or fine steel wool -Laminator (I use a GBC 9” laminator but an iron can be used with varied results) -Ferric chloride or ammonium persulfate -Plastic or glass tray -Sharpie marker -Drill press (a hand drill can work in a pinch) -Wire gauge drill bits -Magazines
Step 1 – Warm up the laminator
Warm up your laminator. This laminator takes about 10-20 minutes to warm up so I plug it in and let it get warm while I work on the following steps. I know you are excited and want to make PCBs, but patience is a virtue and a slightly cool laminator will have you crying in frustration when your board doesn’t work out. Step 2 – Print the Image
Here you might have to experiment with the magazine paper that works best for you. So far a magazine I received from Parts Express has worked better than any other paper I’ve used including the special toner transfer paper. Tear a page out of a magazine (I use a Parts Express catalog), and print your PCB layout onto the page using a laser print. I use a Samsung ML-2010 at 1200dpi with the “lightness decrease” setting. The idea is to print as much toner onto the page as possible. If you have an economy setting on your laser printer then disable it. Cut the PCB to slightly larger than the artwork that you printed out. Then cut out your artwork keeping an edge of paper around the artwork.
Step 3 – Clean the PCB
Cut the board to the correct size for your image. Clean copper board with steel wool, S.O.S. or Brillo pads. Rinse cleaned board with soap and water. Be sure to remove all soap residue. Dry the board completely with a lint free cloth. Do NOT rush this process and make absolute certain that every area of the PCB has been scrubbed and scratched. If you don’t clean the board properly the toner will not adhere properly. Also don’t touch the copper after you’ve cleaned the board. The oils on your skin can keep the toner from sticking.
Step 4 – Transfer the Image
Place your printout face down on the copper clad board. While holding it as flat against the board as possible, begin feeding it into the laminator face up. Once the roller in the laminator grabs the board let it slip through your fingers while maintaining enough drag to keep the paper flat against the board. After about 20 seconds the board will exit the other side of the laminator. Rotate the board 180 degrees and pass it back through the laminator again face up. After it finishes its second pass put the very hot board to the side to cool to room temperature. THE BOARD WILL BE VERY HOT FOR THE NEXT 10 MINS!
Step 5 – Removing the paper
Once your board has cooled to room temperature place the board in a bowl of warm soapy water and let is soak until the paper is soft and mushy (a few minutes). Depending on the magazine paper you may have to peel off the paper or even rub the board with your fingers to remove the part. With the Parts Express magazine it practically falls off. Remove the paper and as much paper residue as you can and lightly dry the PCB with a paper towel. Step 6 – Inspect and correct
Inspect the PCB for any areas that the toner didn’t adhere to or flaked off during the paper removal. Using a Sharpie marker fill in those areas. Chances are you’ll have to fill in a few spots on your boards until you find a paper that works for you. If your PCB is beyond repair with a Sharpie then go back at step two and start over. The beauty is that you aren’t wasting expensive specialty paper, chemicals, or copper clad board when these rare mistakes happen. After making your repairs let the ink from the Sharpie dry.
Step 6 – Etch, Drill, Clean, and Stuff!
I didn’t document this step because this is where methods differ. The most common etchant is ferric chloride which can be picked up at your local Radio Shack or electronics supply store. Others include ammonium persulfate and homebrew mixtures of muriatic acid and hydrogen peroxide. Follow the instructions provided with the type of etchant that you select. After the PCB has etched it is time to drill the pads. I find that a cheap tabletop drill press and wire gauge drill bits work best. You can find both at www.harborfreight.com if your local hardware store is too expensive. You’ve drilled the PCB now it is time to clean off the remaining toner using the scrubbing pad of your choice and nail polish remover. When all of the toner is gone clean the board off with water and dry with a towel. You are ready to stuff and solder your board. At this point you can tin plate the PCB or spray it with a protective conformal coating, but I don’t find it to be necessary. Congratulations!!! You are manufacturing in your bathroom!!!